1. Field of the Invention
The present invention relates to a fastener stringer for a concealed type slide fastener whose fastener element rows in a coupled state are not seen from a tape surface when the fastener element rows in a continuous shape woven along element attaching portions of a pair of right and left fastener tapes are coupled with each other.
2. Description of Related Art
A concealed type slide fastener has a concealing performance of making fastener element rows invisible by coupling the fastener element rows woven along right and left fastener tapes. For this reason, the concealed type slide fastener has been used preferably in various kinds of clothes, shoes and the like by taking an advantage that the concealed type slide fastener does not hamper a design feature due to the concealing performance thereof.
Examples of such a concealed type slide fastener have been disclosed in, for example, Japanese Patent No. 3414110 and Japanese Utility Model Application Laid-Open publication (JP-U) No. 2-132419. In a concealed type slide fastener 54 described in Japanese Patent No. 3414110, as shown in FIG. 5, a fastener tape 42 is woven with a foundation warp yarn 48 and a foundation weft yarn 49, and a coil type fastener element row 41 is woven in an element attaching portion 47 of the fastener tape 42 with a fixing warp yarn 51 and a fixing weft yarn 52 such that coupling heads 44 face inward of the fastener tape 42.
According to Japanese Patent No. 3414110, a plurality of core threads 50 pass on a side of a connecting portion 45 of the fastener element row 41 so that the fixing warp yarn 51 runs over an upper leg portion 46 of the fastener element row 41 and entangles with the foundation weft yarn 49 so as to sandwich the core thread 50 between the upper and lower leg portions 46. Further, the fixing weft yarn 52 is entangled with the fixing warp yarn 51 running between the core threads 50, and runs on an outer face of a core thread 50 on a side of the engaging head 44 so as to be entangled with the foundation weft yarn 49.
A side of a tape main body portion 55 of the fastener tape 42 in which the fastener element row 41 is woven into the element attaching portion 47 is folded back, and with the coupling head 44 of the fastener element row 41 projecting from that folded-back portion, right and left fastener element rows 41 are inserted into a guide path of a slider member 53 so as to constitute the concealed type slide fastener 54. As a result, the fastener element row 41 can be fixed firmly to the fastener tape 42 with simple weaving means, and further, a pitch between elements of the fastener element row 41 can be stabilized.
On the other hand, in a fastener stringer 61 for a concealed type slide fastener described in JP-U-2-132419, as shown in FIG. 6, a fastener tape 62 is woven with foundation warp yarn 78 and foundation weft yarn 79, and a coil-like fastener element row 63 is woven into an element attaching portion 80 formed on a side edge of the fastener tape 62 such that a coupling head 65 faces inward of the fastener tape 62.
In the fastener stringer 61 of JP-U-2-132419, the fastener element row 63 is woven into the fastener stringer 61 with tightening warp yarns 72, 73 running while being entangled with upper and lower leg portions 70, 71 of each element 68, a plurality of upper fixing warp yarns 76 and lower fixing warp yarns 77 running in a warp direction on each of a top surface 74 of the upper leg portion 70 and a bottom surface 75 of the lower leg portion 71 of each element, and a foundation weft yarn 79. The core threads as mentioned in Japanese Patent No. 3414110 are not disposed. According to JP-U-2-132419, the tightening warp yarns 72, 73 are disposed between the respective upper fixing warp yarns 76 and between the respective lower fixing yarns 77, and each of the upper fixing warp yarn 76 and the lower fixing warp yarn 77 is disposed on a coupling head 65 side with respect to the tightening warp yarns 72, 73.
By constructing the concealed type slide fastener using such a fastener stringer 61, an interval between the respective elements 68 of the fastener element row 63 is stabilized so as to prevent breaking of engagement of the chain, and a portion in which the fastener element row 63 is woven can be formed thinner, thereby providing a flexible concealed type slide fastener.
In recent years, the concealed type slide fastener has been more and more widely used due to its advantages, for example, in not only various kinds of clothes and bags but also seat covers for automobile seats and train seats. Thus, the concealed type slide fastener has been demanded to secure a high performance such as concealing performance, flexibility and high coupling strength even if it is used in diversified environments or under diversified conditions.
For example, if specifically speaking of a case where the concealed type slide fastener is used in an automobile seat cover, the seat cover generally covers a cushion body formed in a predetermined shape. At this time, the seat cover is formed in a smaller size than an external dimension of the cushion body, and the cushion body is covered in a compressed state to suppress generation of looseness and deformation in the external shape as much as possible.
Thus, if the concealed type slide fastener is used in the seat cover, fastener tapes of fastener stringers receive a strong lateral pulling force of being pulled from both right and left sides when fastener element rows are coupled with each other or in a coupling state. Therefore, the concealed type slide fastener is demanded not to lose the concealing performance even when the slide fastener receives such a lateral pulling force. The concealed type slide fastener is demanded to have flexibility or constructed with a smaller slider member for a cushion performance or for avoiding losing a tactile feeling of the cushion body.
However, the concealed type slide fastener 54 described in Japanese Patent No. 3414110 lacks flexibility because, as described above, the concealed type slide fastener 54 is constructed so that a plurality of core threads 50 pass in the fastener element row 41, thereby increasing a thickness of the fastener element row 41. Further, a size of the slider member 53 through which the fastener element rows 41 pass is increased, thereby giving a feeling of disharmony in the cushion performance and tactile feeling of the seat cushion.
On the other hand, the fastener stringer 61 of the concealed type slide fastener described in JP-U-2-132419 has an excellent flexibility because a thickness of the fastener element row 63 is small. However, when fastener tapes 62 receive a strong lateral pulling force of being pulled from both right and left sides, a gap is likely to be generated between the fastener tapes 62 on right and left sides. Consequently, the fastener element row 63 is visible on a front surface side, thereby deteriorating the concealing performance inherent in the concealed type slide fastener, which is a problem to be solved.